Heat oven to 350 degrees F.
- Arrange pita wedges in one layer on baking sheets and brush with olive oil. Sprinkle with salt and pepper; Bake just until they start to brown lightly, about 10 minutes. Turn off oven and put chips back in to keep warm.
- Combine yogurt, feta, and parsley and set aside.
- Place lamb and onion in a skillet and cook until lamb is cooked through and onions are tender. Drain off fat. Sprinkle with cumin, oregano, salt and pepper, and cook for an additional 5 minutes. Put chips on a serving plate and top with lamb, sauce, tomatoes, scallions and olives. Serve immediately.